Flyback switching power supply and synchronous rectification drive circuit thereof
A technology of synchronous rectification and switching power supply, which is applied in the direction of high-efficiency power electronic conversion, electrical components, and adjustment of electrical variables. Security, avoiding intercommunication, and reducing the effect of false activation
Pending Publication Date: 2020-10-30
BCD (SHANGHAI) MICRO ELECTRONICS LTD
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Problems solved by technology
At this time, the synchronous rectification controller in the prior art is easy to turn on the controllable switch of the synchronous rectification by mistake, which intensifies the oscillation of the excitation inductance after the mistake is turned on, causing the synchronous rectification controller to continue to turn on by mistake at high frequency; so that once the controllable switch on the primary side is turned on, the Cause the primary and secondary side of the transformer to communicate with each other, and then damage the synchronous rectification controllable switch of the secondary side or cause the explosion
Method used
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[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0034] Please refer to Figure 5 , Figure 5 It is a structural schematic diagram of a synchronous rectification driving circuit of a flyback switching power supply provided by an embodiment of the present invention. The circuit can include:
[0035] The turn-off time detection circuit 11 is used to determine the start-stop result of the s...
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The invention discloses a flyback switching power supply and a synchronous rectification drive circuit thereof, and the circuit comprises: a turn-off time detection circuit which is used for determining a start-stop result of synchronous rectification and a turn-off time detection result of the simultaneous turn-off of a primary side and a secondary side according to a detection voltage outputtedby a synchronous rectification detection voltage output end; a synchronous rectification start-stop controller which is used for generating a corresponding synchronous rectification driving signal according to the start-stop result; and a driver which is used for controlling on and off of a synchronous rectification controllable switch in the secondary winding side circuit according to the turn-off time detection result and the synchronous rectification driving signal. According to the invention, the turn-off time detection circuit is used for detecting the turn-off time of simultaneous turn-off of the primary side and the secondary side, so that the driver can shield the synchronous rectification driving signal output by the synchronous rectification start-stop controller within the turn-off time, the mistaken turn-on condition of the synchronous rectification controllable switch in the Toff time period is reduced, the primary side and secondary side intercommunication phenomenon of the transformer is avoided, and the safety of the flyback switching power supply is improved.
Description
technical field [0001] The invention relates to the technical field of power electronics, in particular to a flyback switching power supply and a synchronous rectification drive circuit thereof. Background technique [0002] At present, there are two types of secondary side rectification schemes for flyback switching power supplies: one is passive, that is, using diodes; the other is using synchronous rectification controllable switches such as power transistors (such as figure 1 and figure 2 shown), a synchronous rectification controller (such as figure 1 and figure 2 The synchronous rectification driver chip) drives the synchronous rectification controllable switch. In a certain power application occasion, using a synchronous rectification controllable switch for synchronous rectification has the characteristics of low power consumption and high system efficiency. Therefore, the temperature characteristics of the entire flyback switching power supply system are also ...
Claims
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Login to View More IPC IPC(8): H02M3/335
CPCH02M3/33592Y02B70/10
Inventor 赵安东谢宜忠
Owner BCD (SHANGHAI) MICRO ELECTRONICS LTD